dressel



i UNITED' STATES 1,666,198- PraN'r OFFICE;

naar. x. ratsam., or cmcaeo, 'marmara alignement mea a'prn 7.

My invention relates to improvements in' sound producers such as radio loud speakers and lthe like, andthe chief characteristic feature is a vibrator comprising a tongue or blade resiliently held against a knife edge across the intermediate portions thereof and subjected at one end to vibrating forces such as a magnetic field controlled by the phone circuit. l0

' provide an-improved .loud speaker or sound producerpwhich is clear in tone and is sensitive to th'e complete range of audible sounds; to provide a sound producer of simplified construction and in which the amplifying horn, having fixed resonances, may be eliminated; to provide a vibrator comprising a suitably mounted blade or resonating plate of large area. which will freely 2.0 and strongly vibrate .to sounds; to fulcrum said blade between the ends -in a suitable manner and apply the magnetic flux or other energizing' means at one end .so that the vibrations are also mechanically amplified; to

.25 provide a blade of such construction .that

the blade may b'e made very thin and of :light material, -in vvhich the vibrations are polarized, and' which is aperiodic: and to rovide magnetic means wherein` the poles are directly on the opposite sides of the vibrator member so that the effect of the field is not'diminished when the member is v1- brating and-periodically. moves'away from the pole or poles at one side. v An illustrative embodiment of my 'invention is shown inthe accompanying drawings, in which;

Fi ure 1 isl a perspective view of" the soun producing unit. A Fig. 2 is a. lan view of the same. Fig. 3 is ta ren on the line 3-3 of Figlm. Fig. 4is an enlarged-fragmentary view taken on the line 4-4 of 4Figure 3.

Fig. 5 shows the vibrator. ln the drawings, a hase or trane l has an integral upright portion 2 at one end and an upright lug 3 at the opposite end.' A fulcrum block4, having. a blunted knife edge 5. is rigidly secured in the frame p ortion 2, A Ushaped yoke 6 is adjustably secured at the ends to the upright portion`2, with a transverse ortion oppositely disposed to the edge 5 of tlie fulcrum member 4 for holding the blade or vibrator -7 against the linear i? bearing 5 ofthe member 4. The linear edge The main objects of my invention are to 'of the corrugations and firmly secured to the Loun Brama Serial In. m38.

5 is shown as bearing directly on the surface of the blade .7, and oni the op ite sid of the blade a stri 'of rubber 8 is interposed between a channe -shapedl bearing block 9, which is secured to th inner face of the transverse portion of the bracket 6, and the surface of the blade. In order'to use very light thin material in the blade and to prevent transverse vibrations, the blade is corrugated longitudinally as shown. The rubber strip 8 conforms to the corrugated surface of the bladeand may be cemented thereto. The opposite legs of the'chahnel member 9 bear one above and one below the linear-edge 5, so as to maintain the blade in an upright position. The'bracket 6 is adjusted to press the blade 7 firml against the linear bearing 5, but the rub r strip opposite the edge precludes tuning the blade to resonate to one single ton'e and renders the blade resonance aperiodic in' character..

VVitlrthe vibrator 7 made of a nonmagnetic material. such as celluloid or bakelite, an iron armature l0, is inserted in the ends- 80 blade by sealing wax or other means.

Since the blade is pivoted in a linear bearing 'between the ends of the blade, the use of magnetson both sides of the armature is available and the electro-magnets l1 and g5 12 are respectively arranged on the opposite A sides of the4 armature 10. thereby equalizing the effect of the magnetic forces when the blade is vibrated'. lVhen. the armature moves away from the poles on one side, with a decrease in the e'ective force of the correspondingr fields, the effect of/'the oles on the opposite side increases. so that t e peaks of the 'vibrations are not distorted.

A s shown in the drawings, the double poled electro-magnet 1l is adjnstably mounted inthe upright frame portion 2, and the opposing electro-magnet 12 is mountedn the lug 3. The magnets are energized in the usual manner. as byA the voice or telephone currents in radio apparatus.

The length of the blade 7, `from the low'er end to the transverse fulcrum 'bearing 5, 'is so proportioned to the total length ofthe blade that. the vibrations at the lower. end are magnified by the leverages obtained.

The vibrations in the audible range areaccurately reproduced, including bpth the high notes and the low notes, and the various characteristics suchas modulation, temper 110 and pitch, the improved `results considered as being largely due to polarizing the vibrations in the blade by corrugating, by4 the iloxx-restraining apex-iodio mounting and by the mechanical amplification. Further improvements comprise applying the magnetic fluxes directly to the vibrator member and by 'arranging the magnets on both sides of the vibrator. y

The4 vibrator .plate is constructed and mounted to vibrate about an axis transverse to the length; also bth sides of the vibrator are unobstructed and therefore both sides are effective for setting the air in motion to carry the sound. (The-mounting is such that the vibrator plate vi'ill return to thel .same neutral ositl'ons, so that permanent adjustments ol the magnets may be made.

Although but one'speeiticjembodiment of 'this invention hasfbeen hereinslloxvn and-- d escribed. it will be .understood t-hat numerous 'detailsvof the construction shown may be altered or omitted without depart-V ing from the spiritof this invention as devfined by the folloi'vingfclaimsz I claim: A 'v 1. In a sound producer', a frame having a' linear bearing, a longitudinally corrugated plate secured between the ends' tothe linear bearing, said being transverse with respect to corrugations of the plate, :and

. Signed at member. for boldingthe plate against the edge. the two edgesof the channel member beingdisposed one above and one below the edge, and a resilient stri p interposed between the edges of the channel member and the plate.

3. AIn a sound producer. a`frame having a knife edge, a vibrator plate, a voke adjustably secured to,v the frame for holding the plate a ainst theedge. a channel member secure to the yoke for pressing' the plate against the knife edge. anda block of resilient material interposed between the two edges of the channel member and the plate.-

4. ln a .loud speaker, a frame having an edge. a vibrator plate; a yoke adjustably sccured tothe framefor holding 4the plate against the edge.` lsaid yoke having bearing portions oneither side of the edge. a block of resilient material interposed between the plate andsaid hearing portions,.and electro-magnets mounted in the frame and disposed on both sides of one end of the plate.' Chicago this 3rd day of April. 1926. f

HENRYM.' DRESSEL. 

